#principal {
   margin:0 auto;
   text-align:center;
} 
.contenedorfoto {
   float:left;
   width:210px;
   height:180px;
   margin: 10px;
   padding:5px;
   background-color:#f5f7f9;
   border-right: #a5a7aa solid 2px;
   border-bottom: #a5a7aa solid 2px;
   text-align:center;
}